EP2820262B1 - Internal combustion engine - Google Patents

Description

The invention relates to an internal combustion engine having an engine block, an air intake line leading from an air inlet to the engine block, an exhaust pipe leading from the engine block to an exhaust gas outlet, an exhaust gas turbocharger whose compressor is arranged in the air intake line and whose turbine is arranged in the exhaust pipe, a diverting air duct, in which a diverter valve is arranged, a first connecting duct, via which an outlet of the compressor is connected to the exhaust duct, an air control valve, which is arranged in the duct, and an oxidation catalyst and a particulate filter, which are arranged in the exhaust duct.

Such internal combustion engines are used for example as diesel engines in motor vehicles. Modern diesel engines have an exhaust gas turbocharger whose compressor to prevent the so-called compressor pumping by means of a diverter valve already compressed air via a bypass from the outlet of the compressor can be fed back to the entrance. These diverter valves are usually pneumatically or electromagnetically switched valves.

In addition, diesel engines have become known in which a connecting line from the outlet of the compressor leads behind the outlet of the turbine in the exhaust pipe. In this connecting line, a control valve is arranged, which serves to regulate the guided into the exhaust pipe air flow. As a result, exhaust gas temperature and oxygen loading in the exhaust gas can be controlled. Furthermore, a too heavy charge at high engine load according to the function of a diverter valve can be prevented.

A correspondingly executed diesel engine is in the DE 101 12 521 B4 disclosed. The connecting line between turbine outlet and compressor outlet opens here before the mouth of a bypass line bypassing the turbine into the exhaust pipe and thus upstream of the exhaust aftertreatment devices, consisting of oxidation catalyst NO _x catalyst and diesel particulate filter. Furthermore, sensors for exhaust gas temperature measurement and oxygen concentration measurement are arranged in the exhaust gas system.

A similar arrangement is from the DE 603 14 611 T2 known. However, in addition to the connecting line, this engine additionally contains a diverting air duct with a diverter valve, but no wastegate duct. The connection line opens downstream of a NO _x catalyst and upstream of a diesel particulate filter with oxidation catalyst in the exhaust pipe. For regeneration of the NO _x catalyst, the engine is operated in the rich state, whereby unburned HC and CO are discharged, but the low oxygen concentration prevents secondary sulfur poisoning. At the same time, the exhaust gas temperature increases. At this time, air is supplied via the connecting line before the diesel particulate filter with catalyst, whereby the HC and the CO are oxidized. Due to this oxidation, the temperature rises, which in turn takes place a regeneration of the particulate filter. To increase the exhaust gas temperature, the throttle valve must be turned on during light load, which reduces the intake manifold pressure and air mass. This results in an enrichment always depending on the boost pressure.

Another such internal combustion engine is in the EP 1 865 169 A2 disclosed. Here, the connection line opens between a three-way catalyst and a particle filter. The introduction of the air serves to increase the exhaust gas temperature for the regeneration of the particulate filter.

In addition is from the JP 2006-233803 an internal combustion engine is known, in which in the outlet line of the compressor of the turbocharger, a switching valve is arranged, via which optionally the compressed air can be passed either in front of a catalyst or back to the inlet of the compressor. A volume control is just as little revealed as the arrangement of the valve in the outlet.

Furthermore, in the FR 2 928 176 discloses an internal combustion engine, wherein in one of the outlet line of the compressor of a turbocharger, a first valve is arranged, via which the branch line can be opened or closed. Behind this valve, a branching space is arranged, branch off from the three lines. One of these lines serves as a diverting air line, in which a further valve is arranged. The second and third line lead to different positions in the region of the exhaust passage of the internal combustion engine. In each of these lines, an additional valve is arranged. All four valves have their own actuator via which they are actuated. The regulation takes place via a common control unit via which the four actuators are actuated for actuation.

Accordingly, there are in the known embodiments, the disadvantages that there is a high component complexity with respect to the necessary control valves to control the operating conditions in low load, full load and regeneration. Furthermore, the arrangement of the air inlet behind the catalysts requires long connecting lines, the assembly of which is complicated. An exhaust gas temperature increase is given by the enrichment of the engine as part of the air removal. To further increase the exhaust gas temperature at the entrance of the particulate filter and to ensure the basic function of the Oxidation catalyst and the particulate filter, the Einregelung a desired oxygen concentration, however, is mandatory.

It is therefore the object to provide an internal combustion engine, which has a low component complexity with good controllability. Thus, optimized oxygen concentrations and exhaust gas temperatures should be adjustable for all load and regeneration conditions.

This object is achieved by an internal combustion engine having the features of the main claim.

The fact that the air control valve and the diverter valve can be controlled by a common actuator, the component cost is reduced. A complete good controllability remains nevertheless. A standardized exhaust throttle on the diesel engine can be omitted in principle, since the purging gradient and the intake air mass can be influenced via the air control valve.

Preferably, the first connection line branches off from the diverting air line. This shortens the length of the necessary piping. Furthermore, the position of the two valves with common actuator in the engine compartment becomes more flexible.

In an advantageous embodiment, the first connecting line opens into the exhaust pipe upstream of the particulate filter. Thus, to regenerate the particulate filter, the required oxygen concentration can also be freely adjusted in cases of raising the exhaust gas temperatures of a rich engine and the resulting low raw oxygen concentration.

Furthermore, it is advantageous if the first connecting line opens into the exhaust gas line upstream of the oxidation catalytic converter. Thus, for the conversion of HC and CO, the temperature can also be significantly increased, for example by post-injection into the oxygen-rich environment, whereby the correct operation of the oxidation catalyst is ensured.

So that a correct control of the exhaust gas temperature, the oxygen concentration in the exhaust gas and the boost pressure is possible, a mass flow sensor is arranged in the first connecting line. Due to the lack of exhaust pollution, a simple air mass sensor can be used here.

Preferably, a second connecting line branches off from the first connecting line, which opens into the exhaust gas line downstream of the diesel particle filter. This should be flowed through in particular during the cold start of the internal combustion engine, since this would lead to a reduction of the heating time of the catalyst, which would then no longer flowed through by relatively cold air. At the same time, the purge gradient in the exhaust gas recirculation in the high-pressure line is increased by the lower amount of air delivered to the engine block, which results in increased recirculation rates with less warm-up time.

For easy implementation of the scheme with two connecting lines from the air intake to the exhaust pipe, a changeover flap is arranged in the branch of the second connecting line, via which either the first or the second connecting line can be closed. Similar to an exhaust gas cooler, the bypass valve can be switched over after the warm-up phase in order to subsequently convey the air for regeneration in front of the catalytic converter and the particle filter.

In a preferred embodiment, the diverting air duct branches off from the air intake duct upstream of an intercooler, so that uncooled air for Increasing the temperatures at the catalyst and the particulate filter in the exhaust pipe is promoted.

A particularly simple construction of the combined valve results when the diverter valve with the air control valve is designed as a 3/2-way valve. This simplifies assembly. Full pre-assembly of the two valves with branching and actuator is possible.

In a particularly simple embodiment, the diverter valve is adjustable with the air control valve closed and the air control valve can be regulated with the diverter valve closed. Such a valve can be realized cost-effectively with a simple freewheel for both valves. Thus, an independent controllability of the flow cross-sections of the connecting line and the diverted return air line is realized.

A particularly cost-effective and durable construction of the combined valve results when the diverter valve and the air control valve are designed as flap valves having a common axis of rotation.

In a particularly preferred further embodiment, the control of the diverter valve and the air control valve via an electric actuator with subsequent transmission, wherein the transmission has a gate, in which a first coupled to the diverter valve for actuation of the bolt engages and a second coupled to the air control valve for actuation Bolt engages, wherein abut in a middle position of the gate, the two bolts against the opposite ends of the gate and close the diverter valve, the thrust air line and the air control valve connecting line.

Thus, an internal combustion engine is created with which a reliable regeneration of the particulate filter and the catalyst can be carried out with reduced component expenditure and at the same time a boost pressure control and air mass control can be carried out independently of the regeneration phases. An exhaust flap can also be omitted as a second actuator for the valves. The pipe lengths are reduced.

• Figur 1 zeigt eine schematische Darstellung einer erfindungsgemäßen Verbrennungskraftmaschine als Schaltbild.
• Figur 2 zeigt schematisch eine Anordnung eines Aktors zum Antrieb eines Luftregelventils und eines Schubumluftventils für die in Figur 1 dargestellte Verbrennungskraftmaschine

An embodiment of an internal combustion engine according to the invention is shown in the figures and will be described below.

• FIG. 1 shows a schematic representation of an internal combustion engine according to the invention as a circuit diagram.
• FIG. 2 schematically shows an arrangement of an actuator for driving an air control valve and a diverter valve for the in FIG. 1 illustrated internal combustion engine

The internal combustion engine according to the invention is in the present embodiment, a 4-cylinder in-line diesel engine having an engine block 10 which is supplied via an air intake 12 with fresh air and the exhaust gas can be removed via an exhaust pipe 14.

In the air intake 12, an air filter 18 and an air mass meter 20 are arranged downstream of an air inlet 16 for determining the intake air mass. The air intake duct leads to an inlet 22 of a compressor 24 of an exhaust gas turbocharger 26. Behind an outlet 28 of the compressor 24, a thrust air duct 30 branches off, via which the outlet 28 of the compressor 24 is fluidically connected to its inlet 22. For controlling the recirculated air mass, a diverter valve 32 is disposed in the diverting 30. Downstream of the branching at which the diverted return air line 30 branches off, a charge air cooler 34 is formed in the air intake line 12, behind which a high-pressure exhaust gas return line 38 opens into the air intake line. In the following, the gas mixture passes via the air intake 12 into the engine block 10 to supply the cylinder 40 of the engine block 10 with fresh air and possibly recirculated exhaust gas.

Exhaust gas discharged from the cylinders 40 exits the engine block 10 via the exhaust passage 14. From the exhaust passage 14, the high-pressure exhaust gas recirculation passage 38 in which an exhaust gas recirculation valve 42 and an exhaust gas cooler 44 are located branches before the exhaust passage 14 enters an inlet 46 of the compressor 24 coupled turbine 48 of the exhaust gas turbocharger 26 opens. Before the inlet 46 branches off a bypass line 50, via which the turbine 48 can be bypassed. The control of the amount of exhaust gas routed via the bypass line 50, which is fed back to the exhaust gas line 14 downstream of a turbine outlet 52, takes place via a wastegate valve 54 arranged in the bypass line 50. Behind the branching of the exhaust gas line 14 with the mouth of the bypass line 50 in the exhaust pipe 14, an oxidation catalyst 56 and a diesel particulate filter 58 arranged for exhaust aftertreatment. The exhaust gas line 14 ends at the exhaust gas outlet 60. A control of the reference variables oxygen concentration and exhaust gas temperature for the determination of regeneration time points takes place by means of a temperature sensor 62 and an oxygen sensor 64, which are arranged directly in front of the catalytic converter 56.

In addition, a first connecting line 66 is provided in the internal combustion engine, via which the outlet 28 of the compressor 24, in the present case via the thrust air line 30 to the exhaust pipe 14 is connected, the mouth of the Connecting line 66 upstream of the catalyst 56 and the diesel particulate filter 58 and the oxygen sensor 64 and the temperature sensor 62 is arranged. In this connecting line 66, a mass flow sensor 68 is designed for controlling the air mass, which is controlled by an air control valve 70, which is arranged in the connecting line 66.

From the first connecting line 66, a second connecting line 72 branches off, which opens into the exhaust gas line 14 downstream of the diesel particulate filter 58. In the branch 74 of the second connecting line 72 from the first connecting line 66, a switching flap 76 is arranged, so that either the first or the second connecting line 66, 72 is flowed through.

According to the invention the air control valve 70 and the diverter valve 32 is actuated by means of a common actuator 78. One possible embodiment of such a combined 3/2-way valve 80, which combines the functions of the diverter valve 32 and the air control valve 70 is in the FIG. 2 shown.

The actuator 78 of this valve 80 consists of an electric motor 82 with subsequent spur gear 96, which are arranged in a housing 84. The valve 80 has an axis of rotation 86 about which a first valve body 88, which forms a valve body of the diverter valve 32, and a second valve body 90, which forms a valve body of the air control valve 70. The first flap body 88 is rotatably mounted on a hollow shaft 92, which penetrates the return air duct 30 and is mounted in a channel-forming housing 93 and the second flap body 90 is disposed on a guided in the hollow shaft 92 shaft 94 which penetrates the connecting line 66.

The electric motor 82 drives a spur gear 96, whose output member is formed by a disc 98, in which a link 100th is formed and whose axis of rotation coincides with the axis of rotation 86 of the shafts 92, 94. The gate 100 extends over half the circumference of the disc 98, wherein the center of the gate is set again by the rotation axis 86. With the hollow shaft 92 is rotatably connected via a lever 101, a first pin 102 which engages in the slot 100 and biased against a first end of the link 100 is applied. The flap body 88 is biased in this position also via a spring element against a housing stop. At the opposite end of the gate 100 is a second coupled to the shaft 94 via a lever 103 bolt 104 biased against a housing stop. Upon actuation of the actuator 78, depending on the direction of rotation, one of the bolts 102, 104 and thus the flap body 88, 90 coupled to it is carried along by the respective end of the link 100 against the spring force, while the other bolt 104, 102 slides in the link 100, because it is pressed by the spring against the stop, and according to the flap body 90, 88 is held in its position.

When reversing the direction of the previously actuated valve body 88 is first rotated by the spring force in its previous position to the stop, while the other is stationary. Subsequently, as soon as the initial position is exceeded, the other flap body 90, 88 is subsequently rotated over the second pin 104 by the now gripping opposite end of the link 100 in the opposite direction, while the other pin 102 slides in the slot 100. Accordingly, either the air flow in the thrust air line 30 or in the first connecting line 66 or depending on the position of the switching flap 76 in the second connecting line 72 can be completely regulated.

During operation of the internal combustion engine can now, for example, due to dynamic changes in the absorption curve of the engine, for example due to switching processes in the automatic process, via the thrust air line 30 to avoid compressor pumping a targeted reduction of the air mass and a map shift of the exhaust gas turbocharger 26 are performed by the diverter valve 32 is opened. When closing the diverter valve 32 and opening the air control valve 70, a targeted enrichment of the internal combustion engine takes place, which has an increase in the exhaust gas temperature while reducing the oxygen content at the turbine outlet result. By introducing the air heated by the compression before the catalyst, the oxygen content is increased again, so that an increase in the exhaust gas temperature can be produced while maintaining the oxygen content of the catalyst, whereby a conversion of HC and CO to CO _{2 is} made possible. Accordingly, optimum conditions for regeneration can be set. A corresponding control of the air masses via the air mass meter 20 and the mass flow sensor 68th

The result is the possibility of independent control of boost pressure and air mass flow, since an increase of the Spülgefälles to increase the recirculated exhaust gas mass is formed when opening the air control valve 70, since to maintain the pressure in the air intake 12, the waste gate valve 54 must be turned on, what an increase in the exhaust pressure in front of the turbine 48 has the consequence. Thus, without the use of a throttle valve or an exhaust valve, the recirculated exhaust gas mass can be increased in the same position of the exhaust gas recirculation valve 42.

In cold start phases, the air can be directed by switching the switching flap 76 via the second connecting line 72 behind the catalyst 56 and the diesel particulate filter 58 in order to achieve a rapid increase in temperature. In addition, a large flushing gradient already exists at low load and low charge pressure between the compressor outlet 28 and the exhaust gas inlet 14.

It follows from all this that with low component complexity and minimized space required a complete control of an internal combustion engine in all necessary operating conditions is made possible. Both a faster heating and a guarantee of regeneration phases and an independent control of the intake air mass and the charge air pressure can be achieved.

It should be clear that the scope of protection is not limited to the embodiment described. Optionally, for example, can be dispensed with the second connection line. Also, the structural design and the coupling of the air control valve and the diverter valve can of course be done in other ways. An additional interdependent control of the two valves is also possible.

Claims (12)

1. Internal combustion engines having
   an engine block (10),
   an air intake duct (12) which leads from an air inlet (16) to the engine block (10),
   an exhaust-gas duct (14) which leads from the engine block (10) to an exhaust-gas outlet (60),
   an exhaust-gas turbocharger (26), the compressor (24) of which is arranged in the air intake duct (12) and the turbine (48) of which is arranged in the exhaust-gas duct (14),
   an divert-air duct (30), in which a divert-air valve (32) is arranged,
   a first connecting duct (66), via which an outlet (28) of the compressor (24) is connected to the exhaust-gas duct (14),
   an air regulating valve (70) which is arranged in the connecting duct (66), an oxidation catalytic converter (56) and a particulate filter (58), which are arranged in the exhaust-gas duct (14),
   characterized in that
   the air regulating valve (70) and the divert-air valve (32) can be regulated via a common actuator (78).
2. Internal combustion engine of claim 1, characterized in that the first connecting duct (66) branches from the divert-air duct (30).
3. Internal combustion engine of one of claims 1 or 2, characterized in that the first connecting duct (66) opens into the exhaust gas duct (14) upstream of the particulate filter (56).
4. Internal combustion engine of one of the preceding claims, characterized in that the first connecting duct (66) opens into the exhaust gas duct (14) upstream of the oxidation catalytic converter (56).
5. Internal combustion engine of one of the preceding claims, characterized in that a mass flow sensor (68) is arranged in the first connecting duct (66).
6. Internal combustion engine of one of the preceding claims, characterized in that a second connecting duct (72) branches from the first connecting duct (66), which second connecting duct opens into the exhaust gas duct (14) downstream of the particulate filter (58).
7. Internal combustion engine of claim 6, characterized in that a changeover flap (76) is arranged in the branch (74) of the second connecting duct (72), via which the first connecting duct (66) or the second connecting duct (72) is selectively closed.
8. Internal combustion engine of one of the preceding claims, characterized in that the divert-air duct (30) branches from the air intake duct (12) upstream of an intercooler (34).
9. Internal combustion engine of one of the preceding claims, characterized in that the divert-air valve (32) is designed as a 3/2-way valve (80) together with the air regulating valve (70).
10. Internal combustion engine of one of the preceding claims, characterized in that the divert-air valve (32) is adapted to be controlled when the air regulating valve (70) is closed, and the air regulating valve (70) is adapted to be controlled when the divert-air valve (32) is closed.
11. Internal combustion engine of one of the preceding claims, characterized in that the divert-air valve (32) and the air regulating valve (70) are designed as flap valves having a common rotary axis.
12. Internal combustion engine of one of claims 10 or 11, characterized in that the divert-air valve (32) and the air regulating valve (70) are controlled via an electric actuator (78) having a downstream transmission (96), the transmission (96) having a slotted link (100) which is engaged by first bolt (102) coupled with the divert-air valve (32) for actuation and by a second bolt (104) coupled with the air regulating valve (70) for actuation, wherein in an intermediate position of the slotted link (100) the two bolts (102, 104) rest against the opposite ends of the slotted link (100) and the divert-air valve (32) closes the divert-air duct (30) and the air regulating valve (70) closes the connecting duct (66).

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